Geographic Range

White-faced sakis (Pithecia pithecia) are located in Brazil, and remote parts of Venezuela. Their range also encompasses most of French Guiana, Guyana and Suriname. They live along the Cuyuni river basin, east of the Caroni River, and south of the Orinoco River. (Veiga and Marsh, 2008)

Habitat

White-faced sakis are arboreal and live in both upland and lowland rainforests. Although they can inhabit very wet and very dry forests, they prefer areas with an abundance of fruit trees and watering holes.
This species is most common at canopy heights of 15 to 25 m. They will also spend time foraging on the ground and at low levels in the understory foliage (3 to 15 m).
Overnight sleeping areas typically are larger trees in the canopy with a wealth of foliage for cover. (Anzelc, 2009; Cunningham and Janson, 2007)

Physical Description

White-faced sakis exhibit sexual dimorphism, with larger males, and sexual dichromatism. Males have a black coat with white fur that surrounds their face. Female sakis have a shorter, brownish grey coat with two vertical lines from their eyes to their nose. Females may also have orange brown colored fur that emerges around the chest area and continues down to their abdomen.
At birth males and adult females are very similar in appearance. A gradual color change over 3.5 to 4 years occurs, in which male sakis become all black with bright white faces.
Sakis have long bushy tails, which are used for balance while jumping from tree to tree. The tails are not used for grasping objects or branches. Average adult mass is 1.8 kg; however, a slight sexual dimorphism separates males (2.38 kg) from females (1.76 kg). (Anzelc, 2009; Fleagle and Meldrum, 1988; Norconk, 2006)

Reproduction

Sakis are known to be monogamous in captivity (zoo environments) although Waters (1995) indicates there have been exceptions in the wild. Anzelc (2009) suggests that monogamy in the wild is less common than expected, and is less common when groups are larger than 2 to 3 individuals. Groups of 4 to 6 are not uncommon, and can include more than one adult breeding male or female. This suggests polygamous or polyandrous mating system, depending on the breakdown of adults in the group. (Anzelc, 2009; Waters, 1995)

Males and females live in small groups. Despite practicing monogamy in zoos, a study of wild sakis in Venezuela found that some sakis were not monogamous. In wild groups, males will make calls to the females during mating season instead of as an alarm call.
Males reach sexual maturity in approximately 32 months. Females are about the same age, but can take several months more. It isn't until the females' ovarian cycle is regular that they are determined sexually mature.
Gestation periods for sakis average 146 days, and females bear 1 offspring at a time. Saki siblings from the previous year or 2 may help care for a newborn saki. (Norconk, 2006)

Females sakis are the predominant caretakers. Infants stay attached to their mother's thigh from birth to 1 month. From age one to four months, the young shift to a dorsal position where they can achieve greater mobility. The mothers carry their infants for the first 3 months. After the infant is around the age of 5 months, the mother will stop carrying it. They feed, protect, and nurture young until they are ready to be on their own. However, infants observe one birthing event prior to leaving their family group. (Norconk, 2006; Waters, 1995)

Lifespan/Longevity

In the wild, white-faced sakis have been known to live about 15 years. One wild-caught saki in captivity lived to the age of 36, spending over 28 of those years in captivity. (de Magalhaes and Costa, 2009)

Range lifespanStatus: captivity

36 (high) years

Average lifespanStatus: wild

15 years

Behavior

Sakis are social but live in small groups of just 2 to 4 individuals. The groups travel together daily, and can easily move 1 to 2 km per day. Most movement occurs in the early morning and early hours of the afternoon. They spend about 9 hours on the move. These activity bouts are relatively shorter than related monkeys, who may be active 10 to 12 hours per day. Sakis are adept leapers aiding in predator avoidance.
Male and female sakis exhibit grooming and mating behaviors, most common between mothers and infants. Male and female sakis teach each other how to raise the young.
In captivity sakis have been known to carry group member's infant. (Anzelc, 2009; Walker, 2005; Waters, 1995)

Females in captivity start to reproduce much earlier in age than they would in the wild, which leads to earlier mortality. After reaching at least 37 months, the survival rate of the individual greatly increases. The longer the female waits to reproduce, the longer she will live. One example of late birthing was observed in an 18-year-old saki who gave birth in a zoo. This saki lived in the wild in its native habitat until she was captured late in life altering her behavior from those reared in captivity. (Waters, 1995)

Home Range

Groups of sakis in Suriname have been known to use a relatively small home range of 10 hectares. Relocated groups utilize much larger home ranges, and reports of 68 to 152 ha were typical. These sakis will mark and defend their territory by a series of activities. Anzelc (2009) summarizes them as "scent gland (sternal/gular/anogenital) rubbing, urine-washing, and territorial calls ....and agonistic interactions, using grunts, trills, branch and body shakes, piloerection, and fast pursuits to threaten and displace extra-group members." (Anzelc, 2009)

Communication and Perception

Sakis live in small groups ranging from 2 to 4 individuals; however larger groups of 6 or more have been reported and may include more than one adult breeding male or female. To establish territory they have loud vocal calls usually performed in duets of monogamous males and females. These duets strengthens their courtship bond. They also socialize by grooming on one another.
White-faced sakis will scent-mark an area. Males rub their chests on trees. They usually choose trees with edible fruit to excite females and to try to stimulate courtship behavior during breeding season. (Anzelc, 2009; Lehman, et al., 2001; Setz and Gaspar, 1997)

Food Habits

Sakis eat the seeds of fruiting bodies. They spend 95 to 99% of total consumption time eating and breaking open the seeds. Year-round, they prefer to eat seeds 38 to 88% of the time. Leaves are also an important source of food. They eat the young leaves of plants during the dry season when fruits are not plentiful. Given this diet, their intake of fats are extremely high, but their intake of proteins are low. On occasion, they have been known to consume insects and flowers when fruit is scarce. (Anzelc, 2009; Norconk and Conklin-Brittain, 2004)

Predation

When a terrestrial predator, such as red-tailed boas, are near sakis will first make an alarm call. Then they will group together and mob the predator in hopes of driving it away. Other terrestrial predators include a weasel called tayras, jaguars, green anacondas, and ocelots.
Their biggest threats are avian predators. Because of their size, sakis are easy prey to the harpy eagle, which are known to attack large primates. A study reported more alarm calls when there is an avian threat, such as an eagle or vulture. When a bird of prey is spotted sakis make the alarm call, which is echoed by group member, and then they stay completely motionless. After time has elapsed, sakis might slip out undetected, heading for lowest parts of the canopy. They try to remain as concealed as possible in the canopy. (Norconk and Gleason, 2002)

Ecosystem Roles

Saki have parasites typical to that of new world monkeys and non-human primates. For example a common parasites are roundworms (Pterygodermatites nycticebi). Heartworms (Dirofilaria immitis) are present in this species, too. They can also get diseases such as diabetes and the Mayaro virus (which is found in mammals that live in trees). (Gamble, et al., 1998; Thoisy, et al., 2003)

Economic Importance for Humans: Positive

White-faced sakis are charaismatic organisms that attract high interest in zoos, however they are recently being exploited for their charisma. There is a market for these monkeys as pets, which is detrimental to the sakis. They are hunted as a source of food by locals. This hurts the population of sakis, because they don't reproduce quickly enough to replace the individuals killed and captured. ("White-Faced Saki Monkey", 2012)

Economic Importance for Humans: Negative

Sakis may carry diseases which can be transferred to humans including the hepatitis virus and the naturally occurring herpes virsus (HSV-1). However, they are not a major disease transmitter. (Schrenzel, et al., 2003)

Conservation Status

This species is not currently listed by IUCN and is of little concern for conservation managers. However, due to habitat destruction and the pet trade, this status could change. It is listed in Appendix II of CITES, indicating that the species could become threatened if trade or import and/or export is not regulated. (Veiga and Marsh, 2008)

Contributors

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

acoustic

uses sound to communicate

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.